title: Relationship between osteoporosis and adipose tissue leptin and osteoprotegerin in patients with chronic obstructive pulmonary disease.
abstract: BACKGROUND
  The role of fat-bone interactions in the pathogenesis of osteoporosis in chronic obstructive pulmonary disease (COPD) is poorly understood. Our aim was to investigate expressions of leptin and osteoprotegerin (OPG) in the adipose tissue, and their relationships to osteoporosis in patients with COPD.
  
  
  METHODS
  In 39 patients with stable COPD, bone mineral density (BMD) and body composition was assessed by Dual Energy X-Ray Absorptiometry. Serum leptin was determined by the enzyme-linked immunosorbent assay, and bone turnover markers osteocalcin and β-crosslaps by the electrochemiluminiscence immunoassays. Subcutaneous adipose tissue samples were analyzed using real-time PCR.
  
  
  RESULTS
  Twenty-one patients without, and 18 with osteoporosis were enrolled (35 men; age 62.2 ± 7.3years). Compared to patients without osteoporosis, those with the disease had significantly lower serum levels and adipose tissue expressions of leptin, in association with increased serum β-crosslaps (p=0.028, p=0.034, p=0.022, respectively). Log adipose tissue leptin was inversely related to serum β-crosslaps (p=0.015), and directly to serum leptin (p<0.001) and to the total, femoral, and lumbar BMD and T-score (p<0.02 for all relationships). Adipose tissue OPG expression was related to all variables of bone density except for lumbar BMD and T-score (p<0.05 for all relationships). Log adipose tissue leptin and OPG expressions predicted femoral T-score independently of age, gender and pulmonary function (p<0.001, adjusted R(2)=0.383; p=0.008, adjusted R(2)=0.301, respectively). Introducing body mass (or fat mass) index into these models eliminated independent predictive value of leptin and OPG expressions.
  
  
  CONCLUSIONS
  Our results suggest that adipose tissue leptin and OPG expressions are related to osteoporosis in patients with COPD, and appear to act as mediators between fat mass and BMD.
authors.affiliation: Department of Respiratory Medicine, and Tuberculosis, P.J. Safarik University, Kosice, Slovakia.
authors.forename: Pavol
authors.initials: P
authors.lastname: Pobeha
authors.forename: Jozef
authors.initials: J
authors.lastname: Ukropec
authors.forename: Peter
authors.initials: P
authors.lastname: Skyba
authors.forename: Barbara
authors.initials: B
authors.lastname: Ukropcova
authors.forename: Pavol
authors.initials: P
authors.lastname: Joppa
authors.forename: Timea
authors.initials: T
authors.lastname: Kurdiova
authors.forename: Martin
authors.initials: M
authors.lastname: Javorsky
authors.forename: Iwar
authors.initials: I
authors.lastname: Klimes
authors.forename: Ivan
authors.initials: I
authors.lastname: Tkac
authors.forename: Daniela
authors.initials: D
authors.lastname: Gasperikova
authors.forename: Ruzena
authors.initials: R
authors.lastname: Tkacova
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D015415:Biomarkers / Q000097:blood; D015519:Bone Density; D016723:Bone Remodeling; D005260:Female; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000150:complications; D020738:Leptin / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000097:blood / Q000150:complications* / Q000378:metabolism* / Q000503:physiopathology; D053244:Osteoprotegerin / Q000235:genetics / Q000378:metabolism*; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000150:complications* / Q000378:metabolism* / Q000503:physiopathology; D012129:Respiratory Function Tests
chemical_list: D015415:Biomarkers; D020738:Leptin; D053244:Osteoprotegerin